In many modern medical procedures, it is common to introduce devices intravascularly so as to minimize the traumatic effect on the patient. For example, in an arteriotomy, wherein an occlusion or blockage of a blood vessel is widened or cleared so as to improve blood flow, it is common to navigate a balloon catheter to the site of the occlusion, inflate the balloon, and thus expand the diameter of the blood vessel in the location of the occlusion. Once expanded, it is often then common to insert a stent to the site of the occlusion so as to hold the blood vessel in an open position and thus prevent the blood vessel walls from contracting radially inwardly after withdrawal of the balloon.
In order to navigate the balloon catheter to the site of the occlusion, it is first necessary to navigate a guide wire to the location. As the balloon catheter itself is relatively soft and malleable, it can not be directed to the site of the occlusion through the blood vessel without a stiffening member along which it can ride. That stiffening member is typically provided in the form of the aforementioned guide wire. Guide wires themselves are relatively stiff or at least have relatively stiff shafts so as to be easily pushed through the blood vessel by the physician or other technician. However, in order to minimize the potential for damage to the blood vessel walls, the distal tip of the guide wire is provided in a relatively soft and malleable form. It is common for the tips of such guide wires to include a polymer sleeve which is soft enough to bend and contort as the guide wire navigates through the sometimes tortuous pathways of the blood vessel, but which also has sufficient strength as provided by the guide wire itself to allow it to be pushed, turned, and otherwise manipulated through the blood vessel. It is still further possible to use a shaping ribbon to provide the very distal tip of the guide wire with improved shape-ability.
While effective, it is still desired in the medical community to provide guide wires with even better performance characteristics. Those characteristics include shape-ability, track-ability and cross-ability. With respect to cross-ability, it is often necessary for the distal tip of the guide wire to cross through the lesion or other occlusion within the blood vessel. Such lesions and occlusions are often relatively hard substances which are difficult for the guide wire to advance through given the need for the guide wire itself to be relatively soft for the purpose of navigating the guide wire through the vasculature. One solution which has been tried has been to make the distal tip of the guide wire relatively hard, but the force with which the guide wire can be advanced is necessarily limited by the overall strength of the entire guide catheter and not just the tip. Accordingly, not only must the guide wire have good cross-ability, i.e., an ability to cross through a lesion or other occlusion, but good shape-ability as well meaning that it can deflect or otherwise deform as the guide wire is navigated through the vasculature.
A still further attribute which guide wires should have is good track-ability, meaning the ability to follow the sometimes tortuous pathways of human blood vessels. In other words, the better the ability of the guide wire to advance through the twists and turns of the blood vessel to get to the site of the occlusion, the better its track-ability.